The present invention relates to control equipment for internal combustion engines, and more particularly to control equipment for internal combustion engines ideally suitable for application to fuel injection engines in which the fuel is injected directly into the cylinder.
In the conventional fuel injection engines in which the fuel is injected directly into the cylinder, as for example described in Japanese Laid-open Patent Publication No. Hei 10-205338, a cavity is provided in the top part of the piston, thereby transporting the fuel spray injected from the fuel injector valve to the neighborhood of the spark plug.
However, since the depth of the cavity formed in the top part of the piston is about 15 mm, there is the problem that the amount of HC in the exhaust gas increases because the fuel sprayed into the cavity gets adhered to the wall surface of the cavity.
In view of this, the present inventors have been investigating a fuel injection internal combustion engine which uses a piston whose top part is either a flat surface or has some shallow grooves several millimeters in depth thereby preventing the adhesion of fuel spray on the piston surface, and the role of the cavity is made to be performed by the flow of the air sucked in, that is, the fuel spray is transported to the neighborhood of the spark plug by air flow (tumble) in the vertical direction. However, in the fuel injection internal combustion engine with such a construction, there was the problem that there may be some situations in which it is not possible to form a combustible air-fuel mixture in the neighborhood of the spark plug at the time of ignition and consequently the combustion becomes unstable.
The purpose of the present invention is to offer a control equipment for internal combustion engines used in fuel injection engines that have the features of not only a cleaner exhaust gas but also of stable combustion.
(1) In order to achieve the above object, according to the present invention, in the control equipment for internal combustion engines in which fuel is injected directly into the cylinder and an air motion control valve is provided in the air suction manifold for adjusting the strength of tumble air motion, the control equipment is provided with a control means that controls the angle of opening of said air motion control valve and the pressure of said injected fuel in accordance with the rotational speed of the engine.
In an internal combustion engine with this configuration, it becomes possible to form a combustible air-fuel mixture in the neighborhood of the spark plug at the time of ignition, and consequently, it is not only possible to make the exhaust gas cleaner but also to obtain stable combustion.
(2) In the above item (1), the piston placed inside said cylinder preferably is one with a flat-shaped top part.
(3) In the above item (1), it is preferable that said control means is provided with a fuel pressure control section that adjusts the pressure of said injected fuel according to the rotational speed of the engine while maintaining constant the angle of opening of said air motion control valve, and a TCV opening angle control section that adjusts the angle of opening of said air motion control valve according to the rotational speed of the engine while maintaining constant the pressure of said injected fuel (fuel pressure), and the control is carried out by switching between said fuel pressure control section and TCV opening angle control section depending on the rotational speed of the engine.